Communication system with improved medium access control sub-layer

ABSTRACT

A communication system which has a plurality of mobile terminals and a base station, each of the mobile terminals and/or base station comprising a medium access control sub-layer, upper layers of the medium access control sub-layer, and a lower layer of the medium access control sub-layer, wherein the medium access control sub-layer is configured to perform self-basic functions in response to basic function execution requests or functions associated with the upper layers or lower layer in response to requests therefrom. According to the present invention, the communication system can provide a compatible multimedia communication service even if an originating terminal and a terminating terminal employ different communication manners, they are available from different manufacturers or they are operated by different communication service operators.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation Application of prior application Ser. No.09/234,518 filed Jan. 21, 1999 whose entire disclosure is incorporatedherein by reference. Further, this application claims the benefit of theKorean Application Nos. 16196/1998 filed on May 6, 1998 in Korea,16345/1998 filed on May 7, 1998 in Korea and 16636/1998 filed on May 9,1998 in Korea, which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to a communication system withmedium access control (referred to hereinafter as MAC) sub-layersprovided respectively in a plurality of mobile terminals and a basestation, and more particularly to a communication system suitable forthe implementation of a multimedia communication service.

2. Description of the Prior Art

Recently, communication systems have very rapidly been developed inevery country. Digital communication systems proposed up to now can beclassified into a frequency division multiple access (FDMA) type, a timedivision multiple access (TDMA) type and a code division multiple access(CDMA) type according to how accesses are established between a basestation and mobile terminals. Only one of the above-mentioned variousaccess systems may selectively be used in some countries or regions.Alternatively, different access systems may simultaneously be used inother countries or regions. For example, the CDMA communication systemand a global system for mobile communication (GSM) are simultaneouslyused in Moscow. To this end, each mobile terminal or base station (ornetwork) is required to comprise two types of modulation/demodulationmodules to compatibly control the two types of access systems. Thisrequirement runs counter to the international communication equipmenttrend of lightness, thinness, smallness and compactness and becomes aprimary factor of weakening the competitiveness of communicationproducts.

On the other hand, even if a single communication system is employed ina certain region, products may be different in function according totheir options and operating systems of mobile terminal manufacturers,other communication equipment manufacturers and communication serviceoperators.

In this connection, a study is being made of increasing thecompatibility of communication equipment to provide a communicationservice to users using the same communication system in the same region,regardless of manufacturers and communication service operators. Therepresentative example may be a Digital European CordlessTelecommunication (referred to hereinafter as DECT) system. This DECTsystem has been developed under the necessity of cordless communicationcapable of accepting data communication requirements to a certain degreewhile giving the first consideration to voice communication.Accordingly, the DECT system can establish interoperability amongcommunication equipment of different manufacturers to provide the userswith various communication services regarding voice and data as extendedoptional services, as well as basic services.

FIG. 1 shows a protocol stack used in a conventional DECT system. Asshown in this drawing, the conventional DECT system is composed of aphysical layer (PHY) 10, a MAC sub-layer 20, data link control layers(DLC1 and DLC2) 30 and 40 and a network layer (NWK) 50.

The PHY 10 of the DECT system functions to divide a given radio spectruminto physical channels. These divisions are made at two domains, or timeand frequency. For the frequency and time divisions, a TDMA operation isperformed with respect to multiple radio carriers. For example, in theconventional DECT system, ten carriers are provided at a frequency bandbetween 1880 MHZ and 1900 MHZ.

The MAC sub-layer 20 of the DECT system basically takes charge of twomain functions. The first function is to select a physical channel andset or release connection of a call on the selected physical channel.The second function is to multiplex control information together withupper layer information and error control information into a packet inthe form of a slot or demultiplex the packet into such information.

The DLC1 30 and DLC2 40 act to provide reliable data links to the NWK50. Also, the DLC1 30 and DLC2 40 are closely connected with the MACsub-layer 20 to provide the upper layer with data integration higherthan that provided single-handed by the MAC sub-layer 20. In FIG. 1, aC-plane is common to all application layers and provides very reliabletransmission links for internal control signals and a limited amount ofuser information traffic. A U-plane is adapted to provide a variety ofalternative services, which are optimized for specific requirements.

The NWK 50 of the DECT system is a main signal layer of the protocolstack. In the conventional DECT system, the NWK 50 employs aconfiguration similar to that in an ISDN layer 3 protocol (ETS 300 102)and provides functions similar to those in the ISDN layer 3 protocol.

In the above-mentioned conventional DECT system, the MAC sub-layeractivates or deactivates a pair of physical channels to control bearercreation, maintenance and release operations, an empty physical channelselection operation and a received signal quality estimation operation.

However, the conventional MAC sub-layer has been developed to besuitable for voice-centered communication systems. For this reason, theconventional MAC sub-layer may be used to perform radio datacommunication to a certain degree, but it will cause many functionalproblems when being applied to multimedia communication service-basednext generation communication systems. Noticeably, the next generationcommunication system will require highly compatible communicationequipment to entirely solve various communication service problemsresulting from option differentiation between communication equipmentmanufacturers and communication service operators and various problemsresulting from different communication manners.

Further, the next generation communication system must be able to selectmany options because it will use multimedia information such as voice,video and text and require very excellent speech quality.

However, the MAC sub-layer of the conventional DECT system is adapted toprovide only two functions, the former selecting a physical channel andthe latter multiplexing control information into a packet in the form ofa slot or demultiplexing the packet into such information. For thisreason, the conventional MAC sub-layer is not applicable to theabove-mentioned multimedia communication service.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made in view of the aboveproblems, and it is an object of the present invention to provide acommunication system which is capable of providing a compatiblemultimedia communication service even if an originating terminal and aterminating terminal employ different communication manners, they areavailable from different manufacturers or they are operated by differentcommunication service operators.

It is another object of the present invention to provide a signalprocessing method for performing various functions required by acommunication system, using improved MAC sub-layers providedrespectively in a plurality of mobile terminals and a base station.

It is yet another object of the present invention to provide a protocoloperating method for executing a communication protocol among improvedMAC sub-layers provided respectively in a plurality of terminals and abase station, according to requests from upper layers of the MACsub-layers.

In accordance with one aspect of the present invention, there isprovided a communication system which has a plurality of mobileterminals and a base station, each of the mobile terminals and/or basestation comprising a medium access control sub-layer; upper layers ofthe medium access control sub-layer; and a lower layer of the mediumaccess control sub-layer, wherein the medium access control sub-layer isconfigured to perform self-basic functions in response to basic functionexecution requests or functions associated with the upper layers orlower layer in response to requests therefrom.

In accordance with another aspect of the present invention, there isprovided a method of processing signals using medium access controlsub-layers in a communication system which has a plurality of mobileterminals and a base station, the medium access control sub-layers beingprovided respectively in the mobile terminals and base station, whereineach of the medium access control sub-layers of the mobile terminalsand/or base station is configured to perform self-basic functions orfunctions associated with upper layers or a lower layer thereof ifsignal processing operations of a corresponding one of the mobileterminals, of the base station or between the corresponding mobileterminal and the base station are requested.

In accordance with yet another aspect of the present invention, there isprovided a method of operating a communication protocol between a basestation and a plurality of mobile terminals using medium access controlsub-layers in a communication system, the medium access controlsub-layers being provided respectively in the base station and mobileterminals, wherein each of the medium access control sub-layers isconfigured to selectively perform an initialization mode step, an idlemode step and a radio resource allocation mode step in response torequests from upper layers thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a block diagram of a protocol stack used in a conventionalDECT system;

FIG. 2 is a block diagram of a protocol stack provided in each mobileterminal or base station in a communication system in accordance with afirst embodiment of the present invention;

FIG. 3 is a block diagram illustrating the entire function of a MACsub-layer in FIG. 2;

FIG. 4 is a block diagram illustrating functions of asynchronization/broadcasting/common control part in FIG. 3;

FIG. 5 is a block diagram illustrating functions of a dedicated/trafficcontrol part in FIG. 3;

FIG. 6 is a flowchart illustrating a method of processing signals usingMAC sub-layers in a communication system in accordance with a secondembodiment of the present invention;

FIGS. 7A to 7J are flowcharts illustrating various signal processingoperations in FIG. 6;

FIG. 8 is a flowchart illustrating a method of processing signals usingMAC sub-layers in a communication system in accordance with a thirdembodiment of the present invention;

FIG. 9 is a view illustrating types of messages used in FIG. 8;

FIG. 10 is a view illustrating formats of the messages in FIG. 9;

FIG. 11 is a view illustrating formats of information elements in themessages in FIG. 9;

FIG. 12 is a view illustrating a format of an establishment cause inFIG. 11;

FIG. 13 is a view illustrating a format of a paging channel number inFIG. 11; and

FIGS. 14 and 15 are flowcharts illustrating a method of operating acommunication protocol between a base station and a mobile terminalusing MAC sub-layers in a communication system in accordance with afourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a block diagram of a protocol stack provided in each terminalor base station in a communication system in accordance with a firstembodiment of the present invention.

With reference to FIG. 2, the protocol stack is composed of a physicallayer (PHY) 10, a MAC sub-layer 100 which is an upper layer of the PHY10, a link access control (referred to hereinafter as LAC) sub-layer 200which is an upper layer of the MAC sub-layer 100, an upper layer 300 ofthe LAC sub-layer 200, and an application layer 400 which is an upperlayer of the layer 300. The upper layer 300 includes a protocoldiscriminator (PD) 310, call reference (CR) 320, call control (CC) 330,mobility management entity (MM-T) 340, radio bearer control entity (RBC)350, radio resource control entity (RRC) 360 and terminal associationcontrol entity (TAC) 370. The application layer 400 includes a callcontrol function (CCF) 410, mobile control function (MCF) 420 and radioaccess control function (RACF) 430.

In the communication protocol of the present invention, the MACsub-layer 100 can perform self-basic functions and functions associatedwith the upper and lower layers.

The basic functions of the MAC sub-layer 100 are a random access controlinformation transfer function, a control information transfer function,a user information transfer function, framing/deframing functions,segmentation/reassembly functions, functions of dividing a LAC frameinto physical channels and vice versa, a CRC function, a MAC sub-layerframe error detection function, and a rate adaptation (padding) functionof adjusting the number of bits suitably for a radio frame.

The associated functions of the MAC sub-layer 100 are a synchronizationinformation control function, a system information control function,physical channel activation/deactivation functions, quality monitoringand reporting functions of, for the maintenance of traffic channelquality (FER), supporting power control, triggering a handover orreporting a channel condition upon traffic channel allocation, and amulti-bearer sequencing function of sequencing a multi-code.

FIG. 3 is a block diagram illustrating the entire function of the MACsub-layer 100 in FIG. 2.

With reference to FIG. 3, the MAC sub-layer 100 includes asynchronization/broadcasting/common control part (SBCCP) 110 fortransferring synchronization information from a base station to aplurality of mobile terminals, setting a dedicated control channelbetween the base station and each of the mobile terminals and performinga call setting operation between the base station and each of the mobileterminals using the set control channel, a dedicated/traffic controlpart (DTCP) 120 for providing a connection-oriented point-to-pointservice to an upper layer of the SBCCP 110 on the basis of abidirectional operation system between the base station and each of themobile terminals and monitoring the quality of a radio link formedbetween the base station and each of the mobile terminals, and a packetcontrol traffic part (PCTP) 130 for providing the connection-orientedpoint-to-point service to the upper layer of the SBCCP 110 on the basisof the bidirectional operation system between the base station and eachof the mobile terminals and implementing a packet data service.

Channels provided in the MAC sub-layer 100 can basically be classifiedinto a common control channel group and a dedicated control channelgroup.

The common control channel group includes a synchronization channel,broadcasting control channel and common control channel, which are alogical type of channels.

The synchronization channel (SCH) is used to transfer time informationfor system time and base information for base station identification.

The broadcasting control channel (BCCH) is used to broadcast generalsystem information. The system information includes access parameterinformation for access to the base station by each of the mobileterminals, adjacent cell information indicative of radio frequency (RF)information of an adjacent cell, and available frequency information.

The common control channel (CCCH) is used to set a stand alone dedicatedcontrol channel (SDCCH) between each of the mobile terminals and thebase station. In the preferred embodiment of the present invention, theCCCH includes a paging channel (PCH) for paging a terminating end, arandom access channel (RACH) for access to the base station by each ofthe mobile terminals, and a forward access channel (FACH) for responseof the base station to the access of each of the mobile terminals. Here,the RACH and FACH are used in pair.

The dedicated control channel group includes the SDCCH, an associatedcontrol channel and traffic channel, which are a logical type ofchannels.

The SDCCH is a connection-oriented bidirectional logical channel formedbetween each of the mobile terminals and the base station. All signalinformation from the setting of the SDCCH till the communication stateare transferred through the SDCCH. For example, terminal association(TA) setup information and call setup information may be transferredthrough the SDCCH.

The associated control channel (ACCH) is a connection-orientedbidirectional logical channel associated with the traffic channel. Allsignal information after the communication state are transferred throughthe ACCH. For example, power control information and handoverinformation may be transferred through the ACCH.

The traffic channel (TCH) is a connection-oriented bidirectional logicalchannel formed between each of the mobile terminals and the basestation. A data transmission rate through the TCH is determinedaccording to the service type.

As shown in FIG. 3, according to the present invention, the MACsub-layer provides extended functions by reflecting a radio environmentin the conventional MAC sub-layer.

In FIG. 3, the synchronization/broadcasting/common control part 110includes a synchronization control entity (SCE) 111 for controlling thesynchronization channel for transferring the system time information andbase station identification information, a broadcast control entity (CE)112 for controlling the broadcasting control channel for broadcastingthe general system information, and a common control channel entity(CCE) 113 for setting and controlling the SDCCH between the base stationand each of the mobile terminals.

The dedicated/traffic control part 120 includes a dedicated controlentity (DCE) 121 for controlling the connection-oriented bidirectionaldedicated control channel formed between each of the mobile terminalsand the base station, and a traffic control entity (TCE) 122 forcontrolling the connection-oriented bidirectional traffic channel formedbetween each of the mobile terminals and the base station and supportinga single or multi-bearer control function (user plane).

The control entities 111-122 are adapted to access the upper layersincluding the LAC sub-layer through three service access points (SAPs).In FIG. 3, MAC_SAPI(=0) is a service access point for the SCE, BCE andCCE, MAC_SAPI(=1) is a service access point for the DCE, andMAC_SAPI(=2) is a service access point for a system management entity ona management plane. Each service access point includes at least oneindependent connection endpoint.

The functions of the synchronization control entity 111, broadcastcontrol entity 112 and common control channel entity 113 in thesynchronization/ broadcasting/common control part 110 will hereinafterbe described in detail with reference to FIG. 4.

The synchronization and broadcast control entities 111 and 112 areadapted to provide a point-to-multipoint service in which the basestation transmits the system time information, base stationidentification information and system information to a plurality ofmobile terminals. These synchronization and broadcast control entities111 and 112 effect the point-to-multipoint service in a store andforward manner. The system information includes access parameterinformation for access to the base station by each of the mobileterminals, adjacent cell information indicative of RF information of anadjacent cell, and available frequency information.

The broadcast control entity 112 is adapted to perform segmentation andreassembly (SAR) operations with respect to a LAC frame according to aframe length of the BCCH. Also, the broadcast control entity 112performs a framing or deframing operation according to a given frameformat.

The common control channel entity 113 provides a random access controlfunction for access between each of the mobile terminals and the basestation. The random access control function is to set the SDCCH betweeneach of the mobile terminals and the base station on the basis of thecommon control channel to effect a point-to-point connectiontherebetween. Each mobile terminal accesses the base station using theset control channel to perform a call setting operation.

The functions of the dedicated control entity 121 and traffic controlentity 122 in the dedicated/traffic control part 120 will hereinafter bedescribed in detail with reference to FIG. 5.

The dedicated control entity 121 is adapted to provide aconnection-oriented point-to-point service to the upper layer. Theconnection-oriented point-to-point service is operated according to abidirectional operation system between the base station and each of themobile terminals. The base station controls a plurality of dedicatedchannels at the same time, and each mobile terminal controls a singlededicated channel.

The traffic control entity 122 provides a radio link quality monitoringfunction which supports power control to physical channels to maintainthe quality (FER) of a traffic frame and triggers a handover if thetraffic frame quality and a pilot intensity fall below predeterminedlevels. Each mobile terminal may measure the radio link quality andreport the measured result to the base station through the ACCH.

On the other hand, the MAC sub-layer can control a plurality of trafficchannels for a multi-bearer connection for a mass service. In the caseof a (multimedia) service call requiring a plurality of codes, amulti-code sequencing function can be performed based on mechanisms forquality of service (QOS) negotiation and dynamic bandwidth allocation.Here, the base station performs resource management, allocation andstate management for a plurality of codes and then transfers theresultant messages to each mobile terminal.

A method of processing signals using MAC sub-layers in a communicationsystem in accordance with a second embodiment of the present inventionwill hereinafter be described with reference to FIGS. 6 and 7A to 7J.

FIG. 6 is a flowchart illustrating an operation of controlling signalsbetween MAC sub-layers of a mobile terminal (MT) and a network (NTWK)(or base station).

With reference to FIG. 6, first, an upper layer (MM1, RBC1 or RRC1) orapplication layer of the MT transfers a desired control command in theform of a primitive to a link access control 1(LAC1) of the MT at stepST31. The LAC1 transfers a request message based on the control commandfrom the upper layer or application layer of the MT to a MAC1 of the MTat step ST32. The MAC1 of the MT sends the request message from the LAC1to a MAC2 of the NTWK sequentially through physical layers (PHY1 andPHY2) of the MT and NTWK at step ST33. Then, the MAC2 transfers therequest message from the MAC1 to a LAC2 of the NTWK at step ST34. TheLAC2 transfers the request message from the MAC2 to an upper layer (MM2,RBC2 or RRC2) or application layer of the NTWK at step ST35 and feeds aresponse signal back to the MAC2 at step ST36. Then, the MAC2 sends theresponse signal from the LAC2 to the MAC1 sequentially through the PHY2and PHY1 of the NTWK and MT at step ST37. Upon receiving the responsesignal from the MAC2, the MAC1 transfers a confirm signal regardingexecution of the initial control command to the LAC1 at step ST38. Then,the LAC1 reports the control command execution to the upper layer orapplication layer.

Noticeably, all control commands do not follow the order shown in FIG.6, and they may be advanced along selective paths according to theircharacteristics.

Operation of Controlling Broadcasting of Synchronization Information orSystem Information

The operation of controlling the broadcasting of the synchronizationinformation or system information provides a point-to-multipoint servicefor time information, system information or paging. This broadcastingcontrol operation effects the point-to-multipoint service in a store andforward manner. Various system parameters received by a mobile terminal(MT) are updated with the latest information.

With reference to FIG. 7A, a radio resource control (RRC) of a network(NTWK) transfers a message in the form of a primitive LAC_UNIT_DATA_REQto a link access control (LAC) of the NTWK at step SA1 or SA11. Uponreceiving the primitive LAC_UNIT_DATA_REQ from the RRC, the LAC of theNTWK transfers a message in the form of a primitive MAC_UNIT_DATA_REQ toa MAC of the NTWK at step SA2 or SA12. Then, the MAC of the NTWK effectsa broadcasting control service for the synchronization information orsystem information in the store and forward manner at step SA3 or SA13.

Upon receiving a synchronization information or system informationrequest message from the MAC of the NTWK a MAC of the MT transfers amessage in the form of a primitive MAC_UNIT_DATA_IND to a LAC of the MTat step SA4 or SA14. Then, the LAC of the MT transfers a message in theform of a primitive LAC_UNIT_DATA_IND to an RRC of the MT at step SA5 orSA15.

Then, the RRC of the MT transfers a primitive MMAC_SYNC_REQ to the MACof the MT at step SA6 or SA16. The primitive MMAC_SYNC_REQ is used fortime synchronization between the NTWK and the MT. Upon receiving theprimitive MMAC_SYNC_REQ from the RRC of the MT, the MAC of the MTtransfers a synchronization information request primitive PHY_SYNC_REQto a physical layer (PHY) at step SA7 or SA17.

Random Access Control Operation

The random access control operation is performed to set an SDCCH betweena mobile terminal (MT) and a network (NTWK) on the basis of the commoncontrol channel to effect a point-to-point connection therebetween. TheMT can access the NTWK through the random access control operation andexecute a call setting operation using the set signal channel.

With reference to FIG. 7B, a LAC of the MT transfers a primitiveMAC_ACC_REQ to a MAC of the MT at step SB1 to request a radio resourcefor setting the SDCCH between the MT and the NTWK. Upon receiving theprimitive MAC_ACC_REQ from the LAC of the MT, the MAC of the MTtransfers a message in the form of a primitive PHY_UNIT_DATA_REQ to aphysical layer (PHY) of the MT at step SB2.

Then, the PHY of the MT sends a primitive PHY_UNIT_DATA_IND to a MAC ofthe NTWK through a physical layer (PHY) of the NTWK at steps SB3 and SB4to notify it that the MT requests the radio resource for the setting ofthe SDCCH.

Upon receiving a channel request message from the MT, the MAC of theNTWK transfers a primitive MAC_ACC_IND to a LAC of the NTWK at step SB5to request the radio resource.

At this time, the MAC of the NTWK transfers an acknowledge message inthe form of a primitive PHY_UNIT_DATA_REQ to the PHY of the NTWK at stepSB6 to acknowledge the channel request from the MT. Then, the PHY of theNTWK sends the channel request acknowledge message from the MAC of theNTWK to the PHY of the MT.

On the other hand, upon receiving the primitive MAC_ACC_IND from the MACof the NTWK, the LAC of the NTWK transfers a primitive MAC_ACC_RSP froman RRC of the NTWK to the MAC of the NTWK at step SB8 to indicate thatthe RRC of the NTWK accepts or rejects the radio resource request. Then,the MAC of the NTWK transfers a message in the form of a primitivePHY_UNIT_DATA_REQ to the PHY of the NTWK at step SB9. The PHY of theNTWK sends a channel response to the radio resource request to the PHYof the MT at step SB10. Upon receiving the channel response from the PHYof the NTWK, the PHY of the MT transfers a message in the form of aprimitive PHY_UNIT_DATA_IND to the MAC of the MT at step SB11. Then, theMAC of the MT transfers a primitive MAC_ACC_CNF to the LAC of the MT atstep SB12 to inform it that the allocation of a new radio resource hasbeen completed.

Physical Channel Activation/Deactivation Control Operations

The physical channel activation/deactivation control operations are toperform control transfer functions for activation/deactivation ofphysical channels. These physical channel activation/deactivationcontrol operations are applied in common to a dedicated signal channeland traffic channel.

With reference to FIG. 7C, an RBC or RRC of a mobile terminal (MT) ornetwork (NTWK) transfers a primitive MMAC_ACT_REQ to a MAC of the MT orNTWK at step SC11 or SC1 to activate a communication path thereto.Alternatively, in order to deactivate the communication path to the MACof the MT or NTWK, the RBC or RRC of the MT or NTWK transfers aprimitive MMAC_DEACT_REQ to the associated MAC at step SC31 or SC21.Then, the MAC of the MT or NTWK transfers a primitive PHY_ACT_REQ to aphysical layer (PHY) of the MT or NTWK at step SC12 or SC2 to activate acommunication path thereto. Alternatively, in order to deactivate thecommunication path to the PHY of the MT or NTWK, the MAC of the MT orNTWK transfers a primitive PHY_DEACT_REQ to the associated PHY at stepSC32 or SC22.

Then, hardware or software of a communication path for the physicalchannel activation or deactivation is set in the PHY of the MT or NTWK.Also, the PHY of the MT or NTWK transfers a primitive PHY_ACT_CNF to theassociated MAC at step SC13 or SC3 to inform it that the communicationpath has been activated. Alternatively, in order to inform the MAC ofthe MT or NTWK that the communication path has been deactivated, the PHYof the MT or NTWK transfers a primitive PHY_DEACT_CNF to the associatedMAC at step SC33 or SC23.

Upon receiving the primitive PHY_ACT_CNF from the PHY of the MT or NTWK,the MAC of the MT or NTWK transfers a primitive MMAC_ACT_CNF to theassociated RBC or RRC at step SC14 or SC4 to inform it that thecommunication path has been activated. Alternatively, upon receiving theprimitive PHY_DEACT_CNF from the PHY of the MT or NTWK, the MAC of theMT or NTWK transfers a primitive MMAC_DEACT_CNF to the associated RBC orRRC at step SC34 or SC24 to inform it that the communication path hasbeen deactivated.

Cell Condition or Channel Condition Reporting Operation

The cell condition or channel condition reporting operation is performedto satisfy a subscriber's service quality requirement upon theallocation of a traffic channel. A mobile terminal (MT) measures a cellcondition or channel condition and reports the measured result to anetwork (NTWK).

Upon receiving a cell condition or channel condition measurement requestfrom an RRC of the MT, a MAC of the MT instructs a physical layer (PHY)of the MT to measure a cell condition or channel condition. The PHY ofthe MT measures the cell condition or channel condition and feeds themeasured result back to the MAC of the MT. Then, the MAC of the MTreports the measured result fed from the PHY of the MT to the RRC of theMT. The RRC of the MT sends the measured result reported by the MAC ofthe MT to the NTWK through a LAC of the MT. As a result, the NTWKallocates a traffic channel on the basis of the measured result from theMT. The NTWK obtains a measurement condition (periodic or as needed) onthe cell condition or channel condition on the basis of a systeminformation message.

With reference to FIGS. 7D and 7E, an RRC of the NTWK transfers aprimitive LAC_UNIT_DATA_REQ to a LAC of the NTWK at step SD1 or SE1 torequest cell condition or channel condition measurement. Upon receivingthe primitive LAC_UNIT_DATA_REQ from the RRC of the NTWK the LAC of theNTWK transfers a message in the form of a primitive MAC_UNIT_DATA_REQ toa MAC of the NTWK at step SD2 or SE2. Then, the MAC of the NTWK sends acell condition or channel condition measurement request message to theMAC of the MT at step SD3 or SE3. Upon receiving the cell condition orchannel condition measurement request message from the MAC of the NTWK,the MAC of the MT transfers a primitive MAC_UNIT_DATA_IND to the LAC ofthe MT at step SD4 or SE4 to request cell condition or channel conditionreport. The LAC of the MT transfers a primitive LAC_UNIT_DATA_IND to theRRC of the MT at step SD5 or SE5 to inform it of the cell condition orchannel condition report request. The RRC of the MT transfers aprimitive MMAC_MEASURE_REQ to the PHY of the MT at step SD6 or SE6 torequest cell condition or channel condition measurement. Then, the PHYof the MT transfers a primitive MMAC_MEASURE_CNF to the RRC of the MT atstep SD7 or SE7 to inform it that the cell condition or channelcondition measurement has been completed.

Upon receiving the primitive MMAC_MEASURE_CNF from the PHY of the MT,the RRC of the MT transfers a primitive LAC_UNIT_DATA_REQ to the LAC ofthe MT at step SD8 or SE8 to inform it of the result of the cellcondition or channel condition measurement requested by the NTWK. Then,the LAC of the MT transfers a primitive MAC_UNIT_DATA_REQ to the MAC ofthe MT at step SD9 or SE9 to inform it of the measured result of thecell condition or channel condition. The MAC of the MT sends themeasured result of the cell condition or channel condition to the MAC ofthe NTWK at step SD10 or SE10. Upon receiving the cell condition orchannel condition measured result from the MAC of the MT, the MAC of theNTWK transfers a primitive MAC_UNIT_DATA_IND to the LAC of the NTWK atstep SD11 or SE1. Then, the LAC of the NTWK transfers a primitiveLAC_UNIT_DATA_IND to the RRC of the NTWK at step SD12 or SE12.

LAC Information Transfer Operation

If a dedicated channel (signal channel or traffic channel) issuccessfully set between a mobile terminal (MT) and a network (NTWK),then it performs two types of information transfer functions, or acontrol information transfer function and a user information transferfunction.

With reference to FIG. 7F, a LAC of the MT or NTWK transfers a primitiveMAC_UNIT_DATA_REQ to a MAC of the MT or NTWK at step SF1 or SF11 torequest control information and user information. Upon receiving theprimitive MAC_UNIT_DATA_REQ from the LAC of the MT or NTWK, the MAC ofthe MT or NTWK transfers a message in the form of a primitivePHY_UNIT_DATA_REQ to a physical layer (PHY) of the MT or NTWK at stepSF2 or SF12. Then, the PHY of the MT or NTWK transfers a message in theform of a primitive PHY_UNIT_DATA_IND to the associated MAC at step SF3or SF13. Upon receiving the primitive PHY_UNIT_DATA_IND from the PHY ofthe MT or NTWK the MAC of the MT or NTWK transfers a message in the formof a primitive MAC_UNIT_DATA_IND to the associated LAC at step SF4 orSF14. As a result, the control information and user information can betransferred from the MT or NTWK to the NTWK or MT.

MAC Cipher Control Transfer Operation

In the MAC cipher control transfer operation, an MM of a mobile terminal(MT) or network (NTWK) requests a cipher operation of a MAC of the MT orNTWK for the protection of data. In practice, the cipher operation isperformed by a physical layer (PHY) of the MT or NTWK and the cipheredresult is transferred to the MM through the MAC.

With reference to FIG. 7G, the MM of the MT or NTWK transfers aprimitive MMAC_CIPHER_REQ to the associated MAC at step SG1 or SG11 torequest the cipher operation. Then, the MAC of the MT or NTWK transfersa primitive PHY_CIPHER_REQ from the associated MM to the associated PHY.

The PHY of the MT or NTWK performs the cipher operation for user dataand then transfers a primitive PHY_CIPHER_CNF to the associated MAC toinform it that the cipher operation has been completed. Upon receivingthe primitive PHY_CIPHER_CNF from the PHY of the MT or NTWK, the MAC ofthe MT or NTWK transfers a primitive MMAC_CIPHER_CNF to the associatedMM at step SG2 or SG12 to inform it that the cipher operation has beencompleted.

MAC Handover Control Operation

The MAC handover control operation is performed to change a radioresource of a specific cell because the radio resource is inferior inquality to that of an adjacent cell. To this end, a MAC of a mobileterminal (MT) or network (NTWK) informs an RRC or RBC of the MT or NTWKof the current radio condition. Then, the RRC or RBC of the MT or NTWKapplies a handover command to the associated MAC. The handover operationis performed by a physical layer (PHY) of the MT or NTWK and thehandover result is transferred to the RRC or RBC of the MT or NTWK.

With reference to FIG. 7H, the MAC of the MT or NTWK measures an errorrate, interference level, pilot signal level, etc. of a receivedtransmission frame. When the measured results reach threshold valuesrequiring the handover operation, the MAC of the MT or NTWK transfers aprimitive MMAC_HO_TRIGGER_IND to the associated RRC or RBC at step SH1or SH11 to request the handover operation. Upon receiving the primitiveMMAC_HO_TRIGGER_IND from the MAC of the MT or NTWK, the RRC or RBC ofthe MT or NTWK transfers a primitive MMAC_HO_REQ to the associated PHYat step SH2 or SH12 to request the handover operation.

Upon receiving the primitive MMAC_HO_REQ from the RRC or RBC of the MTor NTWK, the PHY of the MT or NTWK performs the handover operation andthen transfers a primitive PHY_HO_CNF to the associated MAC to inform itthat the handover operation has been performed. Then, the MAC of the MTor NTWK transfers a primitive MMAC_HO_CNF to the associated RRC or RBCat step SH3 or SH13.

MAC Communication Path Modification Control Operation

The MAC communication path modification control operation is performedto modify a communication path because a cell condition or channelcondition is not good. To this end, an RBC of a mobile terminal (MT) ornetwork (NTWK) requests a MAC of the MT or NTWK to modify acommunication path. Then, the MAC of the MT or NTWK informs theassociated RBC that the communication path has been modified.

With reference to FIG. 7I, the RBC of the MT or NTWK transfers aprimitive MMAC_MODIFY_REQ to a physical layer (PHY) of the MT or NTWKthrough the associated MAC at step SI1 or SI11 to request it to modifyattributes of a communication path.

Upon receiving the primitive MMAC_MODIFY_REQ from the RBC of the MT orNTWK, the PHY of the MT or NTWK performs the requested communicationpath modification operation and then transfers a primitiveMMAC_MODIFY_CNF to the RBC of the MT or NTWK through the associated MACat step SI2 or SI12 to inform it that the communication pathmodification operation has been completed.

MAC Radio Failure Condition Control Operation

In the MAC radio failure condition control operation, a MAC of a mobileterminal (MT) or network (NTWK) informs an RRC or RBC of the MT or NTWKof all failure conditions of a radio environment such as radio resourceinsufficiency, network equipment failure, radio resource use disable,radio resource modification disable, etc. Then, the RRC or RBC of the MTor NTWK requests the associated MAC to stop the setting of a radiobearer, and the MAC of the MT or NTWK informs the associated RRC or RBCof the stopped result.

With reference to FIG. 7J, if a radio communication connection to acommunication path fails, the MAC of the MT or NTWK transfers aprimitive MMAC_RADIO_FAIL_IND to the associated RRC or RBC at step SJ1or SJ11. The RRC or RBC of the MT or NTWK recognizes the radiocommunication connection failure condition in response to the primitiveMMAC_RADIO_FAIL_IND from the associated MAC and then transfers acommunication path deactivation request primitive MMAC_DEACT_REQ to aphysical layer (PHY) of the MT or NTWK at step SJ2 or SJ12 to request itto stop the setting of a radio bearer. Then, the PHY of the MT or NTWKstops the setting of the radio bearer and transfers a primitiveMMAC_DEACT_CNF to the RRC or RBC of the MT or NTWK through theassociated MAC at step SJ3 or SJ13 to inform it that the communicationpath has been deactivated.

FIG. 8 is a flowchart illustrating a method of processing signals usingMAC sub-layers in a communication system in accordance with a thirdembodiment of the present invention.

With reference to FIG. 8, for the provision of a call service between abase station and a mobile terminal through MACs included respectivelytherein, the mobile terminal has to send a channel request message tothe base station through a reverse access channel (RACH). The channelrequest message is used for the request of a radio resource by themobile terminal.

In this connection, the base station receives a message from a specificmobile terminal at step S41 and then checks at step S42 whether thereceived message is a channel request message through the RACH.

If it is checked at step S42 that the received message is not thechannel request message, the base station provides a servicecorresponding to the received message at step S43. To the contrary, inthe case where the received message is the channel request message, thebase station sends a channel request acknowledge message through aforward access channel (FACH) at step S44.

Noticeably, the channel request acknowledge message is used only whenthe mobile terminal tries to access the network through the RACH.

Upon receiving the channel request acknowledge message from the basestation, the mobile terminal stops trying to access the base station atstep S45.

Then, the base station sends a channel response message for channelallocation to the mobile terminal at step S46.

Noticeably, the channel response message is used only when the mobileterminal tries to access the network through the RACH. If the MAC of themobile terminal confirms the channel response message, then it transfersan access response confirm primitive to a link access control (LAC).

A data format of the channel response message is composed of a 1-octetaddress field, a 3-bit MAC frame type and a LAC sub frame.

The mobile terminal is allocated with the requested channel according tothe channel response message from the base station at step S47.

The above-mentioned messages are formatted and sent according to logicalchannel types by the MACs of the mobile terminal and base station.

Namely, as shown in FIG. 9, the logical channel types are classifiedinto a forward access channel (FACH) and a reverse access channel(RACH). The FACH is associated with the channel request acknowledgemessage and channel response message which are sent from the network tothe mobile terminal. The RACH is associated with the channel requestmessage which is sent from the mobile terminal to the network.

Each MAC of the mobile terminal and base station is adapted to determinewhether a received message is the channel request acknowledge message,channel response message or channel request message, by checkinglow-order 3 bits of the received message. That is, as shown in FIG. 10,if the received message is “XXXXX001”, it is determined as the channelrequest acknowledge message associated with the forward access channel.If the received message is “XXXXX010”, it is determined as the channelresponse message associated with the forward access channel. In the casewhere the received message is “XXXXX000”, it is determined as thechannel request message associated with the reverse access channel.TABLE 1 8 7 6 5 4 3 2 1 ADDRESS FIELD RESERVED MAC FRAME TYPE CRC

The above table 1 shows a data frame format of the channel requestacknowledge message. As seen from the above table 1, the data frame ofthe channel request acknowledge message is configured in an A′ typeframe format.

The A′ type frame format is composed of a 1-octet address field region,a reserved region of high-order 5 bits of a 1 octet, a MAC frame typeregion of low-order 3 bits of the 1 octet, and a CRC region for thedetection of a frame error.

A data frame of the channel response message is configured in an A′Btype frame format, as seen from the below table 2. TABLE 2 8 7 6 5 4 3 21 ADDRESS FIELD RESERVED MAC FRAME TYPE CRC INFORMATION PADDING EOF

The A′B type frame format is composed of a 1-octet information region, apadding region of high-order 5 bits of a 1 octet, and an EOF region oflow-order 3 bits of the 1 octet, in addition to the regions in the A′type frame format shown in the table 1. TABLE 3 8 7 6 5 4 3 2 1 ADDRESSFIELD RESERVED MAX FRAME TYPE PAGING SLOT NUM PAGING CH NUM CRC

A data frame of the channel request message is configured in an A typeframe format, as seen from the above table 3.

The A type frame format is composed of a paging slot number region ofhigh-order 4 bits of a 1 octet, and a paging channel number region oflow-order 4 bits of the 1 octet, in addition to the regions in the A′type frame format shown in the table 1.

The channel request acknowledge message, channel response message andchannel request message are configured in the different transmissionframe formats as mentioned above. These messages commonly include a Btype frame format shown in the below table 4. TABLE 4 8 7 6 5 4 3 2 1ADDRESS FIELD RESERVED MAC FRAME TYPE

As seen from the above table 4, the B type frame format includes a1-octet address field region, a reserved region of high-order 5 bits ofa 1 octet, and a MAC frame type region of low-order 3 bits of the 1octet.

The address field consists of a high-order 3-bit establishment cause anda low-order 5-bit random reference.

In this connection, as shown in FIG. 11, information elements,configured by the MAC for the message transmission, are a high-order3-bit establishment cause, low-order 5-bit random reference, 4-bitpaging slot number and 4-bit paging channel number.

The establishment cause represents a random access condition, and therandom reference is a random number produced by the mobile terminalitself. The establishment cause and random reference are used to reducethe probability that two mobile terminals will send messages with thesame random number.

As shown in FIG. 12, the establishment cause indicates different randomaccess conditions according to high-order 3 bits of a 1 octet. Namely,if the high-order 3 bits are “000”, the establishment cause indicates alocation updating condition. Also, the establishment cause represents ananswer to paging condition if the high-order 3 bits are “001”, a calloriginating condition if “010”, a call reestablishment condition if“011”, and an emergency call condition if “100”.

The paging slot number is a value for identifying a specific slot to bemonitored on a paging channel in a slot mode, and the paging channelnumber is a value for identifying a specific paging channel to be usedin the slot mode or a non-slot mode.

The paging channel number identifies a specific paging channel to beused in the slot mode or non-slot mode. Namely, as shown in FIG. 13, ifthe low-order 4 bits are “0000”, the paging channel number indicates anon-slot mode paging channel. If the low-order 4 bits are “0001” to“1111”, the paging channel numbers indicate paging channels 1 to 15,respectively.

In this manner, each MAC of the mobile terminal and base stationconfigures the information elements according to the message type sothat a call service can be provided under a radio environment betweenthe mobile terminal and the base station.

FIGS. 14 and 15 are flowcharts illustrating a method of operating acommunication protocol between a base station and a mobile terminalusing MAC sub-layers in a communication system in accordance with afourth embodiment of the present invention.

In FIG. 14, a communication with the base station is disabled at a nullstep ST1. The reception of synchronization information is waited for ata wait for sync information step ST3. The setting of an SDCCH fororiginating and terminating of the mobile terminal is enabled at an idlestep ST6. Random access is requested and acknowledgment thereof iswaited for at a wait for access ACK step ST15. A response after therandom access acknowledgment is waited for at a wait for access responsestep ST15. The activation of the SDCCH is waited for at a wait foractive step ST18. The SDCCH or radio bearer is activated at an activestep ST21 to enable information transfer therethrough.

In FIG. 15, the setting of an SDCCH for originating and terminating ofthe base station is enabled at an idle step SN1. A mobile terminal'srequest for the SDCCH setting is received and transferred to a LAC, anda response thereto is waited for at a wait for radio resource step SN4.The activation of the SDCCH is waited for at a wait for active step SN7.The SDCCH or radio bearer is activated at an active step SN10 to enableinformation transfer therethrough.

Each of the MAC sub-layers provided respectively in the mobile terminaland base station cooperates with upper layers (MM, RBC, RRC and LAC) anda lower layer (physical layer) to perform an initialization operation,idle mode operation and activation operation. The activation operationincludes a radio resource allocation operation, radio resourceactivation mode operation and radio link failure processing operation.

Initialization Operation Between Mobile Terminal and Base Station

Upon power-on at step ST2, the MAC sub-layer of the mobile terminalproceeds from the null step ST1 to the wait for sync information stepST3. Then, the MAC sub-layer of the mobile terminal starts apredetermined timer and scans a synchronization channel (SCH) to obtainsystem time information and base station identification information fordemodulation.

The MAC sub-layer of the mobile terminal determines whether a validsynchronization information message is received until the timer expires.If no valid synchronization information message is received, the MACsub-layer of the mobile terminal transfers a synchronization acquisitionfailure cause in the form of a primitive MMAC_RADIO_FAIL_IND to theupper layer RRC and then proceeds to the idle step ST6.

In the case where the valid synchronization information message isreceived, the MAC sub-layer of the mobile terminal outputs a command tostop the timer and then transfers system time information and basestation identification information included in the receivedsynchronization information message in the form of a primitivePHY_SYNC_REQ to the physical layer at steps ST4 and ST5 to set a systemtime of the mobile terminal.

On the other hand, the initialization operation of the base station canbe implemented in various manners according to development environmentsand a description thereof will thus be omitted. Noticeably, the basestation must continuously broadcast synchronization information messagesthrough the SCH at a desired period N1 (maximum 1 sec).

Idle Mode Operation Between Mobile terminal and Base Station

First, the MAC sub-layer of the mobile terminal receives a systeminformation message at an idle state and compares an identificationnumber of the received system information with a system informationidentification number stored in the mobile terminal. If theidentification number of the received system information is differentfrom the system information identification number stored in the mobileterminal, the MAC sub-layer of the mobile terminal regards the receivedsystem information as newly modified system information and updates thecurrent system information with the received system information. In thiscase, the MAC sub-layer of the mobile terminal must not communicate withthe base station in any manner until the current system information isupdated.

On the other hand, as shown in FIG. 15, the base station periodicallybroadcasts system information messages through a broadcasting controlchannel (BCCH) at the idle step SN1. At this time, a broadcasting periodmust be within N2 (maximum 1 sec). From a received system informationmessage, the mobile terminal obtains information necessary to theconnection to a base station being currently monitored. In this case,the system information message includes information regarding thecurrent base station, access channel use control information, controlinformation regarding an adjacent base station and CDMA channel listinformation.

Radio Resource Allocation Operation Between Mobile Terminal and BaseStation

The radio resource allocation operation is performed for radioconnection between the mobile terminal and the base station in responseto a radio resource allocation request primitive MAC_ACC_REQ from theupper layer (LAC) of the MAC sub-layer. The primitive MAC_ACC_REQ isused in the MAC sub-layer to request the allocation of a radio resource(signal channel or traffic channel) to be used for registration of theposition of an originating call. Here, the radio resource signifies aradio channel for a point-to-point service between the mobile terminaland the base station, which includes a signal channel (SDCCH) andtraffic channel (TCH).

In the radio resource allocation operation of the mobile terminal, it isfirst checked whether the radio resource is authorized by the basestation. Namely, a system information message broadcasted through theBCCH may include an access authorization level. If the radio resource isauthorized by the base station, then the radio resource allocationoperation of the mobile terminal is started. That is, as shown in FIG.14, upon receiving a primitive MAC_ACC_REQ from the LAC at step ST11,the MAC sub-layer of the mobile terminal sends a channel request messageto the base station at step ST12. The sending of the channel requestmessage is performed by a random access operation. The power control ofan access channel is performed by applying a command regarding atransmission power level to the physical layer according to the systeminformation message broadcasted through the BCCH.

The random access operation can be performed in the following manner.That is, the mobile terminal tries the random access operation throughthe access channel to be allocated with a dedicated signal channel.Parameters used in the random access operation are an establishmentcause which represents a random access condition, a random referencewhich is a random number produced by the mobile terminal itself, apaging channel number which identifies a paging channel, and a pagingslot number which identifies a paging slot.

A confirm operation is performed after the radio resource allocationoperation is completed. This confirm operation is required for thereliable exchange of messages between the mobile terminal and the basestation. The mobile terminal sends a channel request message to the basestation through the random access operation at step ST12. Then, uponreceiving a channel response message from the base station at step ST16,the mobile terminal recognizes that the confirm operation hassuccessfully been performed and then transfers a primitive MAC_ACC_CNFto the LAC at step ST17. The mobile terminal does not start a new accesstry until the current access try is completed.

If the radio resource is set by the channel response message beingreceived by the mobile terminal, then the MAC sub-layer of the mobileterminal proceeds to the wait for active step ST18. Then, the upperlayer (RRC) of the mobile terminal transfers a primitive MMAC_ACT_REQ tothe MAC sub-layer at step ST19, and the MAC sub-layer transfers aprimitive PHY_ACT_REQ to the physical layer at step ST20 to instruct itto activate the allocated radio resource. Then, upon receiving aresponse primitive PHY_ACT_CNF from the physical layer, the MACsub-layer transfers a primitive MMAC_ACT_CNF to the RRC to inform itthat the radio resource has been set.

On the other hand, the radio resource allocation operation of the basestation is performed in the following manner.

Upon receiving the channel request message from the mobile terminal atstep SN2, the MAC sub-layer of the base station sends a channel requestacknowledge message to the mobile terminal at step SN3 to allow themobile terminal to stop the random access try. Then, the base stationallocates the radio resource requested by the mobile terminal theretoand then sends the channel response message to the mobile terminal atsteps SN5 and SN6. The channel response message includes informationassociated with the radio resource allocation, or allocated frequencyinformation and channel allocation description information.

The MAC sub-layer of the base station transfers information regardingthe allocated radio resource to the physical layer to activate aphysical channel at step SN8. Thereafter, signal processing proceduresnecessary to the connection control and call control are performed by apaging control operation. Here, because a point of radio resourceactivation time is a local factor, it may be set differently accordingto development environments.

If the radio resource is set, then the base station ends the radioresource allocation operation. The MAC sub-layer of the base stationtransfers a primitive PHY_ACT_REQ to the physical layer at step SN9 torequest it to activate the allocated radio resource. Then, uponreceiving a response from the physical layer, the MAC sub-layer of thebase station transfers a primitive MMAC_ACT_CNF to the RRC of the basestation at step SN16 to inform it that the radio resource has been set.

Radio Resource Activation Mode Operation Between Mobile Terminal andBase Station

1. Handover Trigger Operation

In each of the mobile terminal and base station, the physical layertransfers a primitive PHY_HO_TRIGGER_IND to the MAC sub-layer to informit that a handover operation must be performed. Then, the MAC sub-layertransfers a primitive MMAC_HO_TRIGGER_IND to the RRC.

2. Radio Condition Measurement Operation

The physical layer of the mobile terminal transfers a primitivePHY_MEASURE_IND to the MAC sub-layer to inform it that a cell conditionor channel condition must be measured. Then, the MAC sub-layer transfersa primitive MMAC_MEASURE_IND to the RRC.

3. Cell Condition Measurement Request Operation

Upon receiving a cell condition report request from the base station,the RRC of the mobile terminal transfers a primitive MMAC_MEASURE_REQ tothe MAC sub-layer. Then, the MAC sub-layer transfers a primitivePHY_MEASURE_REQ to the physical layer to request it to measure the cellcondition. Then, the MAC sub-layer receives a response primitivePHY_MEASURE_CNF from the physical layer.

4. Channel Condition Measurement Request Operation

Upon receiving a channel condition report request from the base station,the RRC of the mobile terminal transfers a primitive MMAC_MEASURE_REQ tothe MAC sub-layer. Then, the MAC sub-layer transfers a primitivePHY_MEASURE_REQ to the physical layer to request it to measure thechannel condition. Then, the MAC sub-layer receives a response primitivePHY_MEASURE_CNF from the physical layer.

5. Cipher Request Operation

In each of the mobile terminal and base station, the MM transfers aprimitive MMAC_CIPHER_REQ to the MAC sub-layer which then transfers aprimitive PHY_CIPHER_REQ to the physical layer to request it to performa cipher operation. Then, the MAC sub-layer receives a responseprimitive PHY_CIPHER_CNF from the physical layer.

6. Handover Processing Operation

In each of the mobile terminal and base station, the RBC transfers aprimitive MMAC_HO_REQ to the MAC sub-layer which then transfers aprimitive PHY_HO_REQ to the physical layer to request it to perform thehandover operation. Then, the MAC sub-layer receives a responseprimitive PHY_HO_CNF from the physical layer.

7. Radio Resource Modification Operation

The radio resource modification operation is to modify attributes of aradio resource being used, according to a new service type (service,transmission rate, etc.).

If the MAC sub-layer receives a radio resource (signal channel andtraffic channel) modification request primitive MMAC_MODIFY_REQ from theRBC, the mobile terminal and base station perform the followingoperations.

The radio resource is activated according to a new service included inthe primitive MMAC_MODIFY_REQ.

The radio resource activation and deactivation operations are performedbetween the MAC sub-layer and physical layer of the mobile terminal onthe basis of primitives PHY_MODIFY_REQ and PHY_MODIFY_CNF. The MACsub-layer of the mobile terminal requests the physical layer to modifyattributes of the radio resource. Then, the MAC sub-layer of the mobileterminal receives a response from the physical layer.

Here, because the radio resource activation and deactivation operationsof the base station are local factors, they may be performed differentlyaccording to development environments.

8. Radio Link Failure Processing Operation

In each of the mobile terminal and base station, if a radio link failsbefore transition from the active state to a different state, thephysical layer transfers a primitive PHY_RADIO_FAIL_IND to the MACsub-layer which then transfers a primitive MMAC_RADIO_FAIL_IND to theRRC or RBC. As a result, the allocated radio resource is released andthe operation then returns to the idle state.

As apparent from the above description, according to the presentinvention, the MAC sub-layer performs the basic functions such as therandom access control information transfer function, control informationtransfer function, user information transfer function, framing/deframingfunctions, segmentation/reassembly functions, functions of dividing aLAC frame into physical channels and vice versa, CRC function, MACsub-layer frame error detection function, and rate adaptation (padding)function of adjusting the number of bits suitably for a radio frame.Further, the MAC sub-layer performs the associated functions such as thesynchronization information control function, system information controlfunction, physical channel activation/deactivation functions, qualitymonitoring and reporting functions, and multi-bearer sequencing functionof sequencing a multi-code.

Therefore, according to the present invention, the MAC sub-layer and theprotocol operating method using the same can provide a compatiblemultimedia communication service even if an originating terminal and aterminating terminal employ different communication manners, they areavailable from different manufacturers or they are operated by differentcommunication service operators.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1-13. (canceled)
 14. A method for allocating a radio resource in awireless communication system, the method comprising: transmitting arequest message to a network for requesting a radio resource allocation;receiving a response message from the network, the response messagecomprising information related to a radio resource allocated by thenetwork; and utilizing the allocated radio resource to transmit data tothe network.
 15. The method of claim 14, further comprising receiving anacknowledgment message from the network for acknowledging receipt of therequest message by the network.
 16. The method of claim 14, furthercomprising receiving a message from the network indicating receipt ofthe request message by the network.
 17. The method of claim 14, whereinthe radio resource comprises a time for transmitting data to thenetwork.
 18. The method of claim 14, wherein transmitting the requestmessage for requesting the radio resource allocation is authorized bythe network.
 19. The method of claim 18, wherein the authorization isreceived via a network broadcast.
 20. A method for allocating a radioresource in a wireless communication system, the method comprising:receiving a request message from a mobile terminal requesting a radioresource allocation; transmitting a response message to the mobileterminal, the response message comprising information related to a radioresource allocated by a network; and receiving data from the mobileterminal via the radio resource allocated by the network.
 21. The methodof claim 20, further comprising transmitting an acknowledgment messageto the mobile terminal for acknowledging receipt of the request message.22. The method of claim 20, further comprising transmitting a message tothe mobile terminal indicating receipt of the request message.
 23. Themethod of claim 20, wherein the radio resource comprises a time for themobile terminal to transmit data.
 24. The method of claim 20, furthercomprising authorizing the mobile terminal to transmit the requestmessage requesting the radio resource allocation.
 25. The method ofclaim 24, further comprising broadcasting the authorization to themobile terminal.